Defining Homogeneous Regions for Streamflow Processes in Turkey Using a K-Means Clustering Method

Dikbaş, Fatih; Fırat, Mahmut; Koç, A. Cem; Güngör, Mahmud

doi:10.1007/s13369-013-0542-0

Cited by 33 publications

(28 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It can be stated that its results include more information on explaining hydrological processes better than the conventional methods, such as Hard K‐Means and Wards' method (Dikbas et al , ). It has been found that FCM is effective in reducing the number of regions to be delineated for RFA (Kulkarni and Kripalani, ; Shu and Burn, ; Dikbas et al , ; Bharath and Srinivas, ), which is based on the minimization of the following objective function:

J_{m} = true {truefalse\sum}_{i = 1}^{N} true {truefalse\sum}_{j = 1}^{C} u_{i j}^{m} true| true| x_{i} - {c_{j}}^{2} true| true|, 1 \leq m < \infty

wherein, m is any real number greater than 1, u ij is the degree of membership of x i in the cluster j , x i is the i th d‐dimensional measured data, c j is the d‐dimension center of the cluster, and ||*|| is any norm to express the similarity between any measured data and the center.…”

Section: Methodsmentioning

confidence: 99%

“…It can be stated that its results include more information on explaining hydrological processes better than the conventional methods, such as Hard K-Means and Wards' method (Dikbas et al, 2012). It has been found that FCM is effective in reducing the number of regions to be delineated for RFA (Kulkarni and Kripalani, 1998;Shu and Burn, 2004;Dikbas et al, 2013;Bharath and Srinivas, 2014), which is based on the minimization of the following objective function:…”

Section: Identification Of Homogenous Regions Through Cluster Analysismentioning

confidence: 99%

See 1 more Smart Citation

A regional frequency analysis of precipitation extremes in Mainland China with fuzzy c‐means and L‐moments approaches

Wang

Zeng

Lai

et al. 2017

Intl Journal of Climatology

View full text Add to dashboard Cite

Owing to their essential influence on human society and natural environment exerted by inducing disasters, such as floods and droughts, further studies on precipitation extremes in China are needed. This study presents the regional frequency and spatial‐temporal patterns of precipitation extremes in China based on a high‐resolution (0.5° × 0.5°) daily precipitation dataset from 1961 to 2013. With fuzzy c‐means, L‐moments methods and other scientific statistical tests, a regional frequency analysis (RFA) is conducted, aiming to further understand the regional and spatial distribution of precipitation extremes across China. The results show that: (1) the whole Mainland China can be divided into 50 homogeneous regions on the basis of the characteristics of mean annual precipitation and location indices. (2) For most of the regions, Generalized Extreme Value (GEV), Generalized Normal (GNO) and Pearson type III (PE3) distributions of precipitation extremes fit well, according to the results of goodness‐of‐fit (GOF) test. (3) For RX1DAY, GEV has the best‐fit distribution in the east, northeast and southwest of China, whereas GNO distribution mostly fits the northern and parts of southwest and southeast; in addition, regions which fit PE3 and Generalized Logistic (GLO) distribute dispersedly across the country. (4) For RX5DAY, GEV mainly fits in the middle, southwestern and southern; GNO and PE3 apply best to the northeastern and northern, respectively. (5) Return periods of 20, 50 and 100 years for their best‐fit distributions decrease gradually from southeastern China to northwestern China. Compared with the results of GEV distribution fitted to each grid, RFA may provide more accurate estimates of rainfall quantiles. Definitely, the study results will not only benefit further understanding of the unique and complex features of extreme precipitation in the whole Mainland China but also contribute to the nation‐scale flood prevention, control and management in the backdrop of the changing climate.

show abstract

J_{m} = true {truefalse\sum}_{i = 1}^{N} true {truefalse\sum}_{j = 1}^{C} u_{i j}^{m} true| true| x_{i} - {c_{j}}^{2} true| true|, 1 \leq m < \infty

Section: Methodsmentioning

confidence: 99%

Section: Identification Of Homogenous Regions Through Cluster Analysismentioning

confidence: 99%

A regional frequency analysis of precipitation extremes in Mainland China with fuzzy c‐means and L‐moments approaches

Wang

Zeng

Lai

et al. 2017

Intl Journal of Climatology

View full text Add to dashboard Cite

show abstract

“…The homogeneous region (HR) concept identifies groups with minimal variation of data within a region, with a larger high spatial variability between regions (Hall and Minns, 2009;Dikbas et al, 2013). There are various approaches for defining regions of hydrologic homogeneity (Borujeni and Sulaiman, 2009;Hosking, 1990;Viglione et al, 2007).…”

Section: Selection Of Homogeneous Regionsmentioning

confidence: 99%

Flow regime change in an endorheic basin in southern Ethiopia

Worku

Werner

Wright

et al. 2014

Hydrol. Earth Syst. Sci.

View full text Add to dashboard Cite

Abstract. Endorheic basins, often found in semi-arid and arid climates, are particularly sensitive to variation in fluxes such as precipitation, evaporation and runoff, resulting in variability of river flows as well as of water levels in endpoint lakes that are often present. In this paper we apply the indicators of hydrological alteration (IHA) to characterise change to the natural flow regime of the Omo-Ghibe Basin in southern Ethiopia. Little water resource infrastructure has been developed in the basin to date, and it is considered pristine. The basin is endorheic and is the main source of flow to Lake Turkana in the East African Rift Valley. The water level in Lake Turkana shows significant fluctuation, but increase of its level can be observed over the past 20 years. The reasons are currently not well understood.Of the five groups of hydrological characteristics in the IHA (magnitude, timing, duration, frequency and variability), only those related to magnitude were found to show significant trends, with the main trend being the increase of flow during the dry season. This trend was not reflected in climatological drivers such as rainfall, evaporation and temperature (which shows a positive trend), but rather is attributed to the substantial changes in land use and land cover in the basin. The change in the basin hydrology is apparent mainly in the more humid part of the basin. The significant shift from forest and woodland to grassland and cropland results in a decrease of actual evaporation and subsequent increase in (dry season) runoff. The long-term trend of the increasing levels in Lake Turkana are related to these trends in dry season flows, while shorter-term fluctuations of the lake levels are attributed primarily to anomalies in consecutive wet and dry season rainfall.

show abstract

“…where χ 2 is the reduced chi-square; RSS is the residual sum of squares; TSS is the total sum of squares; dfE is the error degrees of freedom; I o (t) and I p (t) are the observed and predicted cumulative infiltration (cm) at infiltration time t, respectively; and n is the total number of measurement times. K-means clustering, which is popular for cluster analysis in data mining, aims to partition n observations into k clusters in which each observation belongs to the cluster with the nearest mean, serving as a prototype of the cluster [38]. This results in a partitioning of the data space into Voronoi cells.…”

Section: Model Evaluation and Data Analysismentioning

confidence: 99%

The Scale Effect of Double-Ring Infiltration and Soil Infiltration Zoning in a Semi-Arid Steppe

Liu

Duan

et al. 2019

Water

View full text Add to dashboard Cite

The double-ring infiltrometer is widely used to measure soil unsaturated hydraulic conductivity in the field. The scale effect of the inner and outer ring size (especially the inner one) affects the measurement results. In the semi-arid steppe, where water is scarce and transportation is inadequate, studying the scale effect caused by the inner-ring diameter of the infiltrometer can reduce the test consumption on the premise of ensuring the test accuracy. In this paper, a total of 190 double-ring infiltration tests with different inner-ring diameters (15,20,25,30, and 40 cm) and 0.33 times outer buffer index were carried out at 38 sites with five soil types in the Xilin river basin, China. Results showed that: (1) When comparing the simulated parameters of six infiltration models, parameters increased with the increase of the infiltrometer inner diameter, but the trend gradually slowed down, indicating that the increase of the infiltrometer inner diameter would weaken the influence of the infiltrometer scale effect. However, the infiltrometer with an inner diameter of 40 cm is not enough to completely overcome the scale effect. (2) Through principal component analysis, the infiltration process is mainly affected by the particle size and the initial moisture content. (3) The soil infiltration map based on infiltration tests was more practical than the soil type map, which can provide a theoretical basis for ecological and soil restoration in the future. species diversity does not reduce, but rather improves, the soil erosion resistance [13,14], and finally allows the whole ecosystem to achieve a positive cycle [15].To achieve the goal of obtaining the soil water retention characteristics of the study area, it is necessary to accurately evaluate this capacity, which can be estimated by the final infiltration rate (FIR) and infiltration time when the infiltration rate first reaches the final infiltration time (FIT). A slower infiltration rate indicates that the soil has better water retention [10]. The process of soil infiltration can be simulated in the laboratory using the ring-knife or a soil column [16,17]. However, such studies are influenced by disturbances of the original soil bulk density, porosity, and other soil physical properties. Instead, an infiltration test based on in situ undisturbed soil is capable of reflecting the original state of soil more effectively.Compared with a single-ring infiltrometer, a double-ring infiltrometer can be used to construct an infiltration buffer, which reduces the main external interference factors on the infiltration process of the inner ring [18]. Previous studies have shown that the average infiltration rate increases with the infiltrometer diameter [19,20]. Lai et al. [21] found through a large number of simulations that, compared with the outer buffering index (bi), the inner-ring diameter (di) plays a more important role in obtaining a relatively stable and representative measurement result. When the bi is equal or larger than 0.33, the buffer may meet the measureme...

show abstract

Defining Homogeneous Regions for Streamflow Processes in Turkey Using a K-Means Clustering Method

Cited by 33 publications

References 17 publications

A regional frequency analysis of precipitation extremes in Mainland China with fuzzy c‐means and L‐moments approaches

A regional frequency analysis of precipitation extremes in Mainland China with fuzzy c‐means and L‐moments approaches

Flow regime change in an endorheic basin in southern Ethiopia

The Scale Effect of Double-Ring Infiltration and Soil Infiltration Zoning in a Semi-Arid Steppe

Contact Info

Product

Resources

About